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Changes in soil organic carbon stocks depend on the management regime and a variety of environmental actors including climatic conditions and soil properties. So far, the dynamics of soil organic carbon have not been explicitly represented in global economic land use optimization models. Here, we apply an approach to represent soil organic carbon dynamics explicitly in a global bottom-up recursive dynamic partial equilibrium model using carbon response functions simulated with a biophysical process-based model. We project soil organic carbon emissions from European cropland to decrease by 40% from 64 MtCO2 in 2010 to about 39 MtCO2 in 2050 mainly due to saturation effect when soils converge toward their equilibrium after management, crop rotation, or land use change. Moreover, we estimate a soil organic carbon mitigation potential for European cropland between 9 and 38 MtCO2 per year until 2050 for carbon prices between 10 and 100 USD/tCO2. The total European mitigaion potential including co-benefits from the crop and livestock sector due to the carbon price is even higher with 60 MtCO2 equivalents (eq) per year. Thus carbon sequestration in soils could compensate 7% of total emissions from agriculture within the EU, 10% when including co-benefits from the crop and livestock sector. However, as production is realocated outside Europe with increasing carbon prices, emissions decrease in Europe but increase in the rest of the world (20 MtCO2 eq). Preventing GHG emission leakage to the rest of the world would decrease the European soil organic carbon mitigation potential by around 9% and the total European mitigation potential including co-benefits by 16%. Nevertheless, the net global mitigation potential would still increase. We conclude that no significant contributions to emission reduction targets should be expected from the European cropland carbon sequestration options considered in this study.

Industrialized countries agreed on a reduction of greenhouse gas emissions under the Kyoto Protocol. Many countries elected forest management activities and the resulting net balance of carbon emissions and removals of non-CO 2 greenhouse gases by forest management in their climate change mitigation measures. In this paper a generic dynamic forestry model (FORMICA) is presented. It has an empirical basis. Several modules trace C pools relevant for the Kyoto Protocol and beyond: biomass, litter, deadwood and soil, and harvested wood products. The model also accounts for the substitution of fossil fuels by wood products and bioenergy. FORMICA was used to first study the model sensitivity and uncertainty based on data from Thuringia, a federal state of Germany, to determine the major sources of uncertainty in carbon accounting at different levels of carbon pool aggregation (biomass, ecosystem, forestry sector and enhanced forestry sector including the accumulated substitution effect). Rotation length and maximum increment contributed most to uncertainty in biomass. The influence of the latter did not diminish with higher level of pool aggregation. Uncertainty in the enhanced forestry sector was to a smaller degree controlled by product and substitution related parameters. Relative uncertainty decreased with the level of aggregation and comprehensiveness of the carbon budget. In a second step the model estimated the sink potential of the Thuringian forestry sector. The projected average biomass sink for the period of 2003–2043 of 0.6 t C ha −1 year −1 could be increased by 50% by broadening the perspective to the entire forestry sector, including substitution effects. A simulation of forest conservation on 20% of the forest area increased C fixation. However, even in the biomass C pool the expected C stock changes did not exceed the estimated uncertainty of 40%. A higher level of aggregation (i.e. the inclusion of soil and litter, product pool and substitution effects) decreases relative uncertainty but also diminishes differences between different management options. The analysis demonstrates that the choice of management mitigation options under an accounting scheme should include the impacts on forest products and of substitution effects.